On large semi-trailer and large off-road trucks of the kind employed in road trains and in the mining industry, external rear vision mirrors are provided on both sides of the vehicle cabin of the prime mover. The mirrors have to be mounted some distance out from the cabin so as to provide a clear view for the driver along the full length of the vehicle. The mirrors are therefore also quite large and typically elongated in a vertical direction to provide a sufficiently extensive rear vision view. When the vehicle is moving the mirrors and mirror mounts are subject to environmental conditions causing shear forces, including high shock loads due to ground conditions and therefore they must be securely mounted to ensure the mirrors do not move or change their orientation. On the other hand it must be possible to adjust the position of the mirror, if required, to accommodate different lengths of vehicles, etc. Currently, such adjustment must be done manually by releasing several nuts and bolts, adjusting the position of the mirror and retightening the nuts and bolts. This operation is cumbersome and time-consuming, and obviously cannot be done while the vehicle is moving.
A suitable truck mirror adjusting device is described in co-pending International Application No PCT/AU2010/001252, the contents of which are incorporated herein by reference. This application describes a motorised positioning device for automatically adjusting the position of a mirror on a large vehicle, such as a truck, from inside the vehicle cabin. Whilst this device operates satisfactorily under most conditions, a significant proportion of the weight of the truck mirror is borne directly by a drive shaft of a gearbox in the device.
The present invention was developed with a view to providing a more robust truck rear-view mirror positioning device.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.